The following technologies have been reported as methods for extracting DNA or RNA from a particular single cell or a clump of cells, or from tissue or a portion of tissue.
(1) In one method, a certain portion of cells, a tissue, or a chromosome is cut away using a micro needle while viewed under a microscope. DNA or RNA is extracted from the removed portion. (by S. Noguchi, et al in Cancer Research 54, p1849-1853, 1994 and by Z. Zhuang, et al in American Journal of Pathology vol. 146, No. 3, p620-625)
(2) In another method, a certain cell or tissue is pierced with a micro capillary tube while viewed under a microscope and the contents of the certain cell or tissue are withdrawn through the micro capillary tube. (Proc. Natl. Acad. Sci. USA Vol. 92, p3814-3818, 1995 and in Proc. Natl. Acad. Sci. USA Vol. 89, p3010-3014, 1992)
(3) In a further method, a laser is used to burn off portions other than a target cell or tissue. Afterward, the target cell or tissue is collected and DNA or RNA is extracted from the collected cell or tissue. (Genomics vol. 11, p364-373, 1991)
However, the method using the micro capillary tube requires accurate manipulation of the micro capillary tube under a microscope and so requires a highly-skilled and experienced technician. For this reason, it is difficult to collect the contents of the target cell or tissue only without contamination. Also, although easier manipulation can be anticipated with the method using a laser, it is difficult to completely burn away portions other than the target cell or tissue using a laser. As a result, it is difficult to avoid contamination of the target cell or tissue from surrounding material. For this reason, when DNA or RNA is extracted using the above-described methods and afterward amplified, the contamination will result in an undesirably high background.
It is a purpose of the present invention to provide a simple method for easily separating biological substances, such as certain cells, tissues, biopolymers or low weight biomolecules, for example, biomolecules such as DNA, RNA, protein, or glucose, with little impurities.